Pollutant removal is an integral part of all modern power plant designs. As the pollution control requirements become more stringent, the energy demands for capturing those pollutants become greater. Recirculating (recycling) flue gas with oxygen injection offers the potential for the efficient simultaneous removal of multiple pollutants and CO2 in both retrofits and new power plants. In recirculation of flue gas, the combustion products which are normally sent up the smoke stack at a standard power plant, are recycled back into the boiler after the injection of sufficient oxygen to ensure that the fuel can burn in the mixed gas. A small portion of the flue gas (approximately ¼) is removed from the system. In our approach, this portion of the flue gas is then compressed and cooled to liquefy the condensables (predominantly H2O and CO2).
There is significant energy required to compress flue gas. If the energy of compression is not minimized and partially recovered the power plant thermal efficiency will drop dramatically.